1. Field of the Invention
Aspects of this invention relate generally to an apparatus and method for mounting a device to a pole or other structure having an existing pipe stub, and more particularly to such an apparatus and method for attaching luminaries to new or existing poles for particular lighting applications.
2. Description of Related Art
Pre-existing light poles or other supports and the pipes or pipe stubs extending therefrom on which a particular luminaire mounting is to be attached are known in the art to have varying diameters, varying pipe wall thickness and varying materials such as steel or aluminum. Each pipe may also have a different surface coating, such as zinc, paint, powder coat, and anodizing or natural corrosion. In the case of an outdoor lighting application, the mounting attachment must conform to known criteria required to sustain harsh weather and hurricane force winds. The integrity of this mounting attachment is important in order to secure the luminaire to the manufacturer's specified tightness and central registration for conformance to predetermined performance and light pattern requirements.
More particularly, as is known in the art, there can be variations from one pipe size to another so that half-inch or larger gaps must be accounted for in the pre-existing pipe mounting diameters, thus the attachment means must seal the excess opening between the luminaire and the pipe from insects, small animals and weather intrusion. In the typical application, electrical wires also pass through the pipe stub to connect within the luminaire after the luminaire is secured to the fitting, creating other mounting and sealing challenges.
Luminaire mounting systems of the prior art have shown several methods to attach to the pipe stub. One type may have a simple pipe flange fitting with setscrews spaced equally apart in at least three positions around the circumference of the coupling to be tightened onto the protruding pipe stub. Another type may have one or more compression clamps internal to the luminaire housing that straddle the pipe to compress it against a saddle-shaped base, which requires removal of or opening of an access door to expose the bolts within the clamp and saddle mechanism. And yet another known mounting system is a docking station concept that allows a plug and socket to be secured to the pipe before the luminaire is mounted in order to ensure that attachment to the pipe stub is correctly meeting specification without the nuisance of holding and balancing the luminaire while tightening all bolts to equal tension.
In the known prior art mounting systems herein described, the installer is generally required to hold the luminaire or luminaire mounting base level and stationary while alternately tightening each of the mounting bolts. As in the case of a luminaire with three or more bolts spread around a flange, they are all behind the luminaire from the position of the installer, and in order to keep the pipe centered within the flange, each bolt must be tightened uniformly from behind the luminaire while the installer holds the luminaire in the correct position with his other hand. In a luminaire that must be opened to access the clamp mechanism, there can typically be four clamp bolts that must be alternately tightened to equal tension in order to keep the pipe centered within the clamp.
Each of these previously described installation scenarios in the exemplary context of outdoor pole lighting is an awkward situation for an installer in a lift or bucket truck and as a result sometimes the installation is completed hastily without properly and evenly securing the mount. The integrity of the mounting attachment is the basis of wind load conformance testing, and is that which secures the luminaire to the pole and pipe stub mount during harsh weather such as hurricane force winds. The inconsistency in mounting integrity is demonstrated in practice with the prior art systems when moderate winds can weaken or remove some luminaires and not others despite wind tunnel test results showing sustainability. Integrity may be further compromised if the clamp forces are not even or centered on the pipe to the manufacturer's recommendations. Luminaire attitude or vertical angle adjustment is affected by the pipe stub position in the clamp method or flange screw methods in each of the aforementioned systems; therefore, when a non-zero angle of luminaire attitude adjustment is set, that can and often does adversely affect installation integrity.
The prior art described above teaches luminaire mounting systems that can be installed in various pipes and pipe stubs, but does not teach an apparatus and method including a single tightening point toward the front of the luminaire and thus facing in the direction of the installer and such a system that inherently closes the pipe against the luminaire regardless of the pipe size so as to prevent the intrusion of insects, small animals and weather. Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary.